A steady inflow of oxygen is required to sustain human life. A short interruption or reduction in a person's oxygen supply can rapidly lead to brain or body damage, or death. An individual with too little oxygen in his blood (hypoxemia) or at risk for developing hypoxemia may be given oxygen. An individual able to breathe on his own may be given supplemental oxygen therapy for various reasons and in various places. Oxygen may be given to an individual who has shortness of breath or COPD (chronic obstructive pulmonary disease). Supplemental oxygen may be delivered to a patient who has suffered trauma or an acute myocardial infarction (heart attack). Supplemental oxygen may be given during certain surgical interventions or during post-anesthesia recovery after a surgical intervention. Supplemental oxygen may be given anywhere. It may be given, for example, in a person's home, in a clinic or in a hospital such as in a trauma center, an emergency room, an operating room, a recovery room, or an intensive care unit. A person who is receiving supplemental oxygen therapy is generally weak, injured, or compromised in some way. Such a person is prone to stop breathing briefly or altogether. In order to determine if a person receiving supplemental oxygen is continuing to breathe, an assay may be performed. A non-invasive, expiratory gas sampling device may be used to determine if the person is exhaling as evidence he is continuing to breathe. Commonly, the expiratory gas sampled is carbon dioxide.
Both facemasks and nasal cannula have been used to deliver supplemental oxygen and to sample carbon dioxide. U.S. Pat. No. 5,400,781 to Davenport discloses an oxygen mask with two openings in the floor of the chamber in front of the mouth that lead to an oxygen source and a carbon dioxide monitor. U.S. Pat. No. 5,474,060 to Evans describes an oxygen mask with an inlet for directing a flow of gas (oxygen) to the interior of the mask, and a port for allowing the exhaled air to flow through and a tube for directing the exhaled air to a monitoring apparatus. U.S. Pat. No. 6,247,470 to Ketchedjian uses a flexible lever arm near the face and connected to tubing to deliver oxygen and sample exhaled gases. U.S. Pat. No. 6,439,234 to Curti describes a nasal cannula with two prongs, with the first prong for delivering oxygen and the second prong for sampling carbon dioxide. WO 91/14469 teaches a nasal gas cannula and an oral gas capture member for delivering and capturing carbon dioxide.
Although these facemasks and cannulas attempt to solve some of the problems with delivering oxygen to an individual and determining if he is breathing, none provides an easy to use, universal device that can deliver oxygen and sample an expiratory gas in a variety of circumstances. The present invention is directed to meeting these, as well as other, needs.